Soil and ground water contaminations are frequent and often found around automotive garages, under heating oil storage tanks, near manufacturing plants, paint shops and in parking areas of industrial machinery for examples. The contaminants found at these locations are various and include in most cases hydrocarbons such as paint thinner, gasoline, fuel, kerosene, lubricants, bunker C oil and even pitch. In other words, the range of contaminants commonly found in contaminated soils and ground water contains numerous petroleum products including polycyclic aromatic hydrocarbons (PAH's). These are the contaminants that are of interest herein, and are often referred to hereinafter as Light Non-Aqueous Phase Liquids (LNAPL contaminants).
In the past, various methods have been used for cleaning soils contaminated with petroleum-based and organic contaminants. One of the best known method is referred to in the art as an "ex-situ" process which includes excavation and transport of the contaminated soil, and treatment of this soil at a remote location. A second best known method is an "in situ" process, which comprises the steps of leaching a remediation solution through a contaminated soil and pumping out the solution containing the emulsified contaminants, from one or more wells reaching below the contaminated region. Examples of in situ and ex-situ remediation processes are described in the following patents:
U.S. Pat. No. 4,869,825 issued on Sep. 26, 1989 to W. Steiner; PA0 U.S. Pat. No. 4,997,313 issued on Mar. 5, 1991 to T. L. Gibson et al.; PA0 U.S. Pat. No. 5,011,329 issued on Apr. 30, 1991 to J. M. Nelson et al.; PA0 U.S. Pat. No. 5,035,537 issued on Jul. 30, 1991 to J. L. Rose; PA0 U.S. Pat. No. 5,160,217 issued on Nov. 3, 1992 to N. Metzer et al.; PA0 U.S. Pat. No. 5,161,914 issued on Nov. 10, 1992 to P. L. Rahn et al.; PA0 U.S. Pat. No. 5,249,888 issued on Oct. 5, 1993 to K. E. Braithwaite et al.; PA0 U.S. Pat. No. 5,263,795 issued on Nov. 23, 1993 to J. C. Corey et al.; PA0 U.S. Pat. No. 5,342,147 issued on Aug.30, 1994 to F. C. Payne et al.; PA0 U.S. Pat. No. 5,449,251 issued on Sep. 12, 1995 to W. D. Daily et al.; PA0 U.S. Pat. No. 5,509,760 issued on Apr. 23, 1996 to F. E. Schriefer et al.; PA0 U.S. Pat. No. 5,553,974 issued on Sep. 10, 1996 to D.Nazarian; PA0 Canadian Patent Application 2,089,639, published on Feb. 14, 1993 by L. M. Purcell et al.; PA0 U.S. Pat. No. 5,156,686 issued on Oct. 20, 1992 to D. C. Van Slyke; PA0 U.S. Pat. No. 5,252,138 issued on Oct. 12, 1993 to E. P. Guymon; PA0 U.S. Pat. No. 5,376,183 issued on Dec. 27, 1994 to S. Gatt et al.; PA0 U.S. Pat. No. 5,525,008 issued on June 11, 1996 to J. T. Wilson. PA0 Canadian Patent 1,322,862 issued on Oct. 12, 1993 to T. Cseh et al.; PA0 Canadian Application for Patent 2,042,599 published on Apr.11, 1991 by B. E. Peacock; PA0 U.S. Pat. No. 5,154,831 issued on Oct. 13, 1992 to S. T. Darian et al.; PA0 U.S. Pat. No. 5,286,386 issued on Feb. 15, 1994 to S. T. Darian et al.; PA0 U.S. Pat. No. 5,306,351 issued on Apr. 26, 1994 to W. J. Anderson; PA0 U.S. Pat. No. 5,427,688 issued on Jun. 27, 1995 to T. M. Sivavec; PA0 U.S. Pat. No. 5,634,983 issued on Jun. 3, 1997 to N. Kammeraad; PA0 U.S. Pat. No. 5,660,613 issued on Aug. 26, 1997 to R. L. Bernier et al.; PA0 U.S. Pat. No. 5,711,020 issued on Jan. 20, 1998 to N. L. Wolfe et al.; PA0 U.S. Pat. No. 5,817,187 issued on Oct. 6, 1998 to T. F. D'Muhala et al.; PA0 U.S. Pat. No. 5,922,665 issued on Jul. 13, 1999 to A. Liu; PA0 U.S. Pat. No. 5,928,433 issued on Jul. 27, 1999 to R. W. Jahnke et al;
It is believed that the most commonly used in situ remediation process is as disclosed in the U.S. Pat. No. 4,997,313 mentioned above. In this process, an aqueous surfactant solution is applied to the soil and is allowed to penetrate the soil and leach through the contaminated region. The leachate is removed from a recovery well at the middle of the contaminated region. Pumping is done at a rate of about twice the flow of injection of the remediation solution to the soil so as to reduce the water level in the region of the well, to induce a flow of leachate from the above soil formation into the well. This in situ method is also referred to as a "pump-and-treat" process wherein the leachate and the contaminated ground water are pumped from the underground to the surface and treated to separate the contaminants. The treated ground water is then returned underground.
The prior art also contains several emulsifier and surfactant compositions for cleaning a contaminated soil, whether the method is carried out in situ or ex-situ. Examples of remediation compositions of the prior art are found in the following patents:
It is also known that some of the soil remediation compositions of the prior art contain one or more of the TRITON.TM. surfactants or their chemical equivalents. TRITON.TM. surfactants arc manufactured by Union Carbide Corporation from Danbury, Conn., USA. The following patents are specific examples of remediation compositions containing one or more of the TRITON surfactants.
In the past, the in situ or pump-and-treat remediation method has been preferred to the ex-situ process, basically for cost consideration and for not disrupting the terrain. However, these in situ methods are generally tedious, can require years to perform, and may never fully return the soil and ground water to an acceptable condition to serve as a drinking water aquifer.
Therefore, it is believed that a continuing need exists in the art for remediation compositions and accompanying methodology, to clean contaminated soils and ground water more efficiently, reliably, economically and safely than has heretofore occurred with conventional methods.